The present invention relates to an ink jet printing apparatus.
Ink jet printers are known in the art which print a dot on a sheet with a single drop of ink. However, these printers are only suitable for high contrast printing since there are no means for varying the printing density as is required for continuous tone printing in various shades of gray.
Improved ink jet printers have been developed comprising nozzles designed to eject a stream or jet of ink which breaks up into a stream of minute particles. The ink particles are electrostatically charged and deflected onto a sheet where it is desired to print a dot. In this manner, the dots are formed by a cluster or group of tiny ink particles. The widths of the charging pulses may be varied to thereby vary the relative number of ink particles in the clusters and the printing density of the dots. However, these printers have not been developed to a fully satisfactory state.